In a printer in gaming applications, such as casinos, a ticket being printed is valid when the validation number is successfully printed out, whether or not the rest of the ticket printed successfully or not. Once the validation number is printed, the central system determines that this ticket is valid even though the remaining ticket could be blank. This valid ticket may now be cashed in, and the gaming institution provides money to the player. However, if the number is not successfully printed, then the ticket is not valid, and the player cannot collect their money. Therefore it is important to know the position of the ticket within the printer, and whether or not the validation number has been printed on the ticket.
It is generally difficult to know the position of the paper within a printer, and paper tracking has been limited to sensors at fixed distances in the paper path detecting black marks or paper edges. If the operator pulls or holds the paper, he or she may create a paper jam. There is a possibility that the paper jam occurs right before or after the printing of the validation number on the ticket. If the exact position of the ticket within the printer is known, then it may also be known whether the validation number has been printed.
Prior attempts have been made to determine the position of paper within a printer, for example, in U.S. Pat. No. 4,690,577 (Kikuchi) a mechanical sensor lever is employed to determine the presence of paper in the paper path. In U.S. Pat. No. 5,132,531 (Duncan) an optoelectric position-sensitive detector using projected light is disclosed, which may be used to determine the presence of paper within a paper path. In U.S. Pat. No. 5,507,583 (Beaty), the invention describes an infrared light to determine when label stock is in position for printing. In U.S. Pat. No. 5,041,850 (Kahoyashi) a position sensor employs a photoelectric transducer element which detects paper position, and the presence and position of labels, by changes in transmissivity of the light. In U.S. Pat. No. 5,988,905 (Abe) the use of light is also described as a manner to determine the paper position with a sensor which is transversely displaceable.
In U.S. Pat. No. 6,672,705 (Kitahara), the belt speed/position sensor detects the number of mark lines that have passed as the count is initiated by the paper tip. By knowing the number of mark lines, the sensor also knows the position of the paper. In U.S. Pat. No. 6,609,844 (Petteruti et al) the position of the centering mechanism may be magnetically encoded, and a sensor reads the encoded position of the centering mechanism.
In U.S. Pat. No. 7,198,265 (Chelvayohan), a media sensor device, composed of a light reflectance sensor, is mounted to the drive shaft, wherein as the drive shaft is rotated one in one direction, the sensor is moved out into the paper path, and if the drive shaft is rotated in the opposite direction, the sensor is moved outside of the paper path. In U.S. Pat. No. 6,914,684 (Bolash), non-linear characteristics of light sensors are used to detect the media-type, such that a ratio between two sensors accurately determines the glossiness and presence of the media.
Although there has been some prior art in the way of position sensors for paper or tickets that are being fed through a printer, it has largely revolved around optical sensors which sense a page beginning or ending or through the use of markings on the page to know the position. It is valuable to know the position of the paper or ticket, to avoid paper jams and malfunctions, as well as facilitating movement back and forth of the paper or ticket under the print head. Since there is no effective solution to know the position of a paper or ticket without markings on the paper, there is therefore a need for an economical and practical solution to determining the paper position within the printer.